Hello. I would like to find an analytical solution of the one group point kinetic equations with the external source. I have a critical reactor and I would do the step change in reactivity. I would like to find the solution for n(t). The ONE-GROUP point kinetics equations: dn/dt=([tex]\rho[/tex]-[tex]\beta[/tex])/[tex]\Lambda[/tex]*n(t)+[tex]\lambda[/tex]*c(t)+Q dc/dt=[tex]\beta[/tex]/[tex]\Lambda[/tex]*n(t)-[tex]\lambda[/tex]*c(t) I can solve the equations using Laplace transformations, but I don`t know the initial conditions: c(0) and n(0), since the reactor is critical I can`t use the stationary initial conditions? What can I do. Thanks.